Hot flashes occur in as many as two thirds of U.S. women during menopause and are severe enough to require treatment in 20%. Although postmenopausal hormone therapy is an effective treatment, it is associated with increased risk for a variety of serious adverse effects. There is currently an urgent need for alternative treatments that are effective, safe, and easy to use. Prior small clinical trials have reported that slow breathing (slow-paced respiration) can significantly reduce the frequency of hot flashes by reducing sympathetic nervous system activity, which has been found to be increased in women with hot flashes. However, paced respiration is rarely used to treat hot flashes, because data supporting efficacy are limited, and there is no clear description of how to teach or learn the technique. To provide clear evidence of the efficacy and feasibility of using slow-paced respiration to treat hot flashes, we propose to conduct a rigorous randomized, blinded trial using a simple, easy-to-use device (RESPeRATE, Intercure Inc.), that guides users to slow their respiration below 10 breaths per minute (BPM). The device, which is commercially available (Costco, Amazon) and approved by the FDA for treatment of mild hypertension, includes a belt-type respiration sensor that is placed around the chest over clothing, along with a small computerized box that generates musical patterns through earphones. Sensing the users respiration, the device synchronizes its musical tones to the users inspiratory and expiratory phases. As the user follows the pattern of the musical tones, respiratory rate is slowed and expiration is prolonged. For the proposed clinical trial, we will enroll 120 women with at least 4 menopausal hot flashes per day and randomize them either to use the device to practice slow-paced respiration for 15 minutes per day for 12 weeks, or to use the device to practice listening to relaxing music without pacing respiration for 15 minutes per day for 12 weeks. Our specific aims are to: 1) determine the efficacy of slow-paced respiration using the RESPeRATE device to reduce the frequency of hot flashes (measured using an ambulatory sternal skin conductance monitor); 2) determine the efficacy of slow-paced respiration using RESPeRATE on other symptom and quality-of-life outcomes associated with hot flashes (i.e., self-reported severity of hot flashes, bothersomeness of hot flashes, difficulty sleeping, menopause-related quality of life, depression symptoms, and anxiety symptoms as measured by validated questionnaires); and 3) determine if improvement in frequency of hot flashes with paced respiration is mediated by reduction in sympathetic nervous system activity, relative increase in parasympathetic activity, or parameters of slow-paced respiration. This research will definitively demonstrate whether this novel behavioral intervention that targets autonomic nervous system activity offers an effective and feasible alternative to estrogen for alleviation of hot flashes.